I've had trouble a few times now with different distros and unetbootin. I've had more consistent success with universal-live-usb installer from pendrive linux. I use a windows version though, don't know if they have a linux version.

Or, you could use the Easy2Boot method for creating a multiboot USB thumb drive where the iso images are easily replaced. It appears to recreate faithfully the iso image(s) as burnt onto CD/DVD, yet unlike the dd command, keeps the thumb drive read/writable.

Unetbootin takes over or replaces the iso's boot menu with its own. In Easy2Boot, you choose from the E2B main menu which iso image you wish to bootup, and instead of directly booting the image, it brings you to the original boot menu of that particular iso image, just like if you were running it from CD/DVD.

See link below. The final post gives you the simplest way of preparing your thumb drive so you probably can ignore the rest of the thread, where you can see me asking lots of questions. Ultimately it was much simpler than I made it out to be.

I'm a bit late to the party and its looking like the OP wants to give Kubuntu a good try. But let me add my 2cents anyway.

As mentioned, rolling releases are never "stable" by nature. At least that has been my experience. However, if you want to try a rolling release that is based on Debian, I highly recommend SolydK. They base the Home Editions on Debian Testing. They do quarterly updates of a "testing" snapshot that has been tested against their changes and bugs are worked out the best they can. Its quite good for a rolling release. However, it is still a rolling release. Things usually go flawlessly, but it seems about once a year one of the updates will have issues that need resolving. They are not typically big issues and the forum is great, but if you don't want to mess with repairing updates, a rolling release is not for you.

Then there is SolydK BE (Business Edition). It is a pretty pure Debian Stable base with some SolydK touches added. So it has an improved updated managager, device driver manager and other Solyd tools. I switched from Mepis 11 to SolydK BE and have found it to be an excellent replacement. However, since it is based on Debian Stable, packages are older. If the OP wants newer packages, Kubuntu might be the better option.

My last thought would be to check out Mageia. They are a fixed release on a 9 month update cycle with 18 month support cycle. This would provide newer software but it would also required periodic updates. As a bonus, the Mageia Control Center (Mandrake Control Center) is a beautiful tool. I wish there was something similar available in Debian.

So there are my thoughts. I think Kubuntu is a good distro and its always one I consider as well. But if I ever get tired of Debian I am moving to Mageia, just for the control center.

Asqwerth, that looks like a good tip; I've bookmarked that last post; it'd be cool to have Kubuntu, antiX, and PartedMagic all on one USB (and carry a Plop Linux CD in case of a machine that can't natively boot from USB). And Fargo, as you note, rolling is never stable -- I was after rolling just because I'm tired of having to do a clean install every couple years. I found Kubuntu (and the rest of the Ubuntu family) offer upgrades, which will give me what I wanted from rolling: freedom from installing fresh.

Right now, I've got Pipelight up and running in Kubuntu 64-bit (though I might have to revert to 32-bit if I can't find a way to get the 64-bit video drivers to cooperate with 32-bit Flash; my games are being blocked by a black box), everything else is doing what I want, and I'm pretty sure I'm becoming Kubuntu-stable. I won't be wiping my Mepis partition any time soon, though, just in case...